Large aspect ratio seal window flexure for aerial optical imaging systems

Abstract

This invention discloses a flexible mechanism for a large-diameter-to-thickness sealing window used in an airborne optical imaging system, belonging to the field of optical component installation and adjustment technology. The mechanism includes an optical window frame, an O-ring seal, an optical window, an optical window retaining ring, a flexible support, and an outer cylinder for the optical window. The optical window is installed inside the outer cylinder, and their contact surfaces are bonded together with sealant. The optical window retaining ring is fixed to the outer cylinder to assist in fixing the optical window. The outer cylinder is connected to the flexible support. The flexible support is connected to the optical window frame, and both its upper and lower end faces have sealing grooves with built-in O-ring seals. This invention effectively eliminates stress on the optical window caused by temperature gradients and pressure differences in the radial and axial directions through the flexible support, avoiding stress concentration and solving the deformation problem of large-diameter-to-thickness airborne windows. Simultaneously, multiple seals ensure overall airtightness, significantly improving the imaging quality of airborne cameras in harsh environments.

Description

Technical Field

[0001] This invention relates to the field of optical element installation and adjustment technology, and in particular to a flexible mechanism for a large diameter-to-thickness sealing window used in aerospace optical imaging systems. Background Technology

[0002] With the rapid development of aerospace platforms, optoelectronic payloads are facing increasingly stringent requirements in terms of high altitude, high speed, and high resolution. The high-aspect-to-thickness sealed window of an aerial camera, as a zero-optical-power optical element, is crucial for ensuring the optical system acquires high-precision image information due to its high environmental adaptability. The harsh operating environment of aerial cameras, including impacts and vibrations from the carrier, and pressure and temperature variations within and outside the payload, can all cause deformation of the sealed optical window, leading to a decrease in image quality.

[0003] The sealed optical window, located at the forefront of the entire optical imaging system, serves as the interface between the internal load and the external environment. During operation, the uneven heat exchange between the inner and outer sides of the window creates non-axisymmetric temperature gradients (including axial and radial temperature gradients). Axial temperature gradients can cause defocusing, while radial temperature gradients can lead to edge collapse or warping of the window glass, introducing wavefront errors. Simultaneously, the pressure difference between the inside and outside disrupts the window's stress balance, causing it to bulge outwards, introducing additional stress, resulting in surface deformities and changes in optical path difference. Therefore, a sealed optical window must not only possess sufficient rigidity, strength, and airtightness but also withstand the effects of pressure and temperature differences without stress concentration. Traditional engineering methods for supporting large aspect ratio windows (10–25) are insufficient to meet these stringent requirements.

[0004] Based on the aforementioned technical problems, those skilled in the art urgently need to develop a flexible sealing window mechanism with a large diameter-to-thickness ratio for aerospace optical imaging systems that can reduce the impact of the support method on the wavefront error of the optical system, improve the performance of the optical window and the imaging quality of the optical system, and ensure clear imaging of the optical system in high-altitude working environments. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible mechanism for a large diameter-to-thickness sealing window for an aerospace optical imaging system, in order to solve the problems in the prior art where large diameter-to-thickness sealing windows for aerospace systems are prone to introducing additional stress when working in harsh environments, resulting in deterioration of the window surface shape, increased wavefront error, and decreased imaging quality.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The present invention relates to a flexible sealing window mechanism for a large diameter-to-thickness ratio sealing window in an aerospace optical imaging system, the flexible mechanism comprising: Light window frames and optical windows; and An outer tube for the optical window, wherein the optical window is installed inside the outer tube for the optical window, and the contact end face between the optical window and the outer tube for the optical window is bonded together with sealant; The light window retaining ring is fixedly connected to the outer cylinder of the light window and abuts against the optical window to assist in fixation; A flexible support is connected to the light window frame. Both the upper and lower ends of the flexible support are provided with sealing grooves, and sealing elements are installed in the sealing grooves. The outer cylinder of the light window is connected to the flexible support.

[0007] Preferably, the sealing element is an O-ring, which is placed inside the sealing groove; Furthermore, the light window frame forms an end-face seal with the flexible bracket through the O-ring.

[0008] Preferably, the sealant is silicone rubber, and the end face of the outer cylinder of the light window is provided with an annular groove for coating the silicone rubber.

[0009] Preferably, the optical window retaining ring and the optical window are in a clearance fit or zero preload contact to reduce the preload on the optical window.

[0010] Preferably, the flexible support is configured to release the strain of the optical window caused by temperature gradient or pressure difference in the radial and axial directions, thereby eliminating optical window stress.

[0011] Preferably, the optical window is a ZnS-MS aerospace window with a large aspect ratio.

[0012] Preferably, the outer cylinder of the light window, the flexible bracket, and the light window frame are coaxially connected in sequence to form an integral sealed structure.

[0013] Preferably, the outer cylinder of the light window is connected to the flexible bracket by a threaded connection or a screw connection.

[0014] Preferably, the flexible support is a thin-walled elastic structural component.

[0015] Preferably, the light window pressure ring is connected to the light window outer cylinder by a threaded connection.

[0016] The large-diameter-to-thickness ratio sealing window flexible mechanism for aerospace optical imaging systems provided by the present invention has the following beneficial effects: The large-diameter-to-thickness ratio sealed window flexible mechanism for aerospace optical imaging systems of the present invention has the function of eliminating optical window stress caused by temperature difference. During the operation of the photoelectric load, the non-uniform heat exchange between the inner and outer sides of the aerospace sealed window causes a large asymmetric temperature gradient in the optical window, mainly including axial temperature gradient and radial temperature gradient. The flexible support can release the strain of the optical window in the radial and axial directions, eliminating optical window stress; This invention has the function of eliminating the stress of the optical window caused by pressure difference. During the operation of the photoelectric load, there is a pressure difference between the inner and outer sides of the aviation sealed window. The pressure difference will cause the force balance of the window glass to be disrupted, and the window will tend to bulge outward, introducing additional stress and causing the surface shape of the window glass to deteriorate. The flexible support can release the strain of the optical window in the axial direction and eliminate the stress of the optical window. This invention features a sealing function. The optical window is housed within an outer cylinder, and the contact surface between the optical window end face and the outer cylinder is bonded with sealing silicone rubber. The sealing silicone rubber is applied to an annular groove in the outer cylinder to ensure uniform adhesive layer thickness and achieve sealing between components. A flexible support is connected to the optical window frame, with both its upper and lower end faces sealed by O-rings to ensure a tight seal between the flexible support and the optical window frame. This mechanism ensures the overall sealing performance of the flexible sealing window mechanism through the bonding of silicone rubber and the use of built-in O-rings. Meanwhile, this device has a wide range of applications and can be widely used in aviation fields such as military reconnaissance, disaster relief, meteorological detection, and geographic mapping where large diameter-to-thickness sealing windows are required. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0018] Figure 1 A three-dimensional structural diagram of a flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system provided in an embodiment of the present invention; Figure 2 A side cross-sectional view of a flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system provided in an embodiment of the present invention; Figure 3 A side upper sectional view of a flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system provided in an embodiment of the present invention. Figure 4 This is a lower side cross-sectional view of a flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system provided in an embodiment of the present invention. Figure 5A front view of a flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system provided in an embodiment of the present invention; Figure 6 A cross-sectional view of the optical window in a flexible sealing window mechanism for an aerospace optical imaging system with a large diameter-to-thickness ratio, provided in an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: 1. Window frame; 2. O-ring seal; 3. Optical window; 4. Window pressure ring; 5. Flexible support; 6. Window outer cylinder. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0021] See Figures 1-6 As shown; The large-diameter-to-thickness ratio sealing window flexible mechanism for an aerospace optical imaging system of the present invention mainly includes an optical window frame 1, an O-ring seal 2, an optical window 3, an optical window retaining ring 4, a flexible support 5, and an optical window outer cylinder 6. This mechanism is used to isolate the aerospace camera optical imaging system from the external environment, ensuring a relatively stable imaging environment for the optical system. Its core design principle is to ensure that the optical window is in a balanced state, without over-constraint or under-constraint, preventing additional stress and torque, while simultaneously meeting sealing requirements.

[0022] As a preferred technical solution in this embodiment, the optical window 3 is installed inside the outer cylinder 6 of the optical window. A sealing silicone rubber is uniformly coated into the annular groove on the end face of the outer cylinder 6, and then the contact surfaces of the optical window 3 and the outer cylinder 6 are bonded together using this sealing silicone rubber, ensuring a uniform adhesive layer thickness and achieving a flexible seal between the two.

[0023] In this preferred embodiment, the optical window retaining ring 4 is fixed to the outer cylinder 6 of the optical window via a threaded connection or other means. Its inner edge gently abuts against the outer end face of the optical window 3, serving only as an auxiliary fixing function. Unlike traditional methods that require a large preload to ensure a seal, the sealing performance of this invention is mainly ensured by the silicone rubber adhesive layer. Therefore, a large preload is not required on the optical window retaining ring 4, avoiding deformation or stress of the optical window 3 due to excessive clamping force. This is particularly important for optical windows with relatively low elastic modulus (such as ZnS-MS).

[0024] As a preferred technical solution in this embodiment, the outer cylinder 6 of the optical window is then connected to the flexible support 5 by screws or threads. The flexible support 5 is designed as a thin-walled elastic structural component, capable of generating controllable elastic deformation in the radial and axial directions. When the optical window 3 experiences strain due to temperature gradient or internal and external pressure difference, this strain is transmitted to the flexible support 5 through the outer cylinder 6, where it is absorbed and released by the elastic deformation of the flexible support 5, thereby eliminating the internal stress transmitted to the optical window 3 and avoiding stress concentration.

[0025] Finally, the flexible bracket 5 is connected to the light window frame 1. Sealing grooves are formed on both the upper and lower end faces of the flexible bracket 5, and O-rings 2 are placed within these grooves. When the flexible bracket 5 and the light window frame 1 are assembled and pressed together, the O-rings 2 are compressed, forming an end-face seal and ensuring the airtightness of the interface between the flexible bracket 5 and the light window frame 1.

[0026] Through the multi-stage sealing method described above—"optical window-silicone rubber adhesive seal" and "flexible bracket-O-ring end face seal"—the overall sealing performance of the entire window mechanism is achieved. This invention is particularly suitable for large aspect ratio ZnS-MS aviation windows with an aspect ratio of up to 24, effectively solving the stress deformation problem in harsh aviation environments and ensuring clear imaging.

[0027] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A flexible sealing window mechanism with a large diameter-to-thickness ratio for use in an aerospace optical imaging system, characterized in that, The flexible mechanism includes: The light window frame (1) and the optical window (3); and The optical window outer cylinder (6) is installed inside the optical window outer cylinder (6), and the contact end face of the optical window (3) and the optical window outer cylinder (6) is bonded together with sealant. The light window retaining ring (4) is fixedly connected to the outer cylinder (6) of the light window and abuts against the optical window (3) to assist in fixation; A flexible support (5) is connected to the light window frame (1). Both the upper and lower ends of the flexible support (5) are provided with sealing grooves, and sealing elements are installed in the sealing grooves. The outer cylinder of the light window (6) is connected to the flexible support (5).

2. The flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system according to claim 1, characterized in that, The sealing element is an O-ring (2), which is placed in the sealing groove; Furthermore, the light window frame (1) forms an end face seal with the flexible bracket (5) through the O-ring seal (2).

3. The flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system according to claim 1, characterized in that, The sealant is silicone rubber, and the end face of the outer cylinder of the light window (6) is provided with an annular groove for coating the silicone rubber.

4. The flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system according to claim 1, characterized in that, The optical window retaining ring (4) and the optical window (3) are in clearance fit or zero preload contact to reduce the preload on the optical window (3).

5. The flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system according to claim 1, characterized in that, The flexible support (5) is configured to release the strain of the optical window (3) caused by temperature gradient or pressure difference in the radial and axial directions to eliminate optical window stress.

6. The flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system according to claim 1, characterized in that, The optical window (3) is a large aspect ratio ZnS-MS aerospace window with an aspect ratio of 24.

7. The flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system according to claim 1, characterized in that, The outer cylinder of the light window (6), the flexible bracket (5), and the light window frame (1) are coaxially connected in sequence to form an overall sealed structure.

8. The flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system according to claim 1, characterized in that, The outer tube of the light window (6) is connected to the flexible bracket (5) by means of threaded connection or screw connection.

9. The flexible sealing window mechanism with a large diameter-to-thickness ratio for an aerospace optical imaging system according to claim 1, characterized in that, The flexible support (5) is a thin-walled elastic structural component.

10. The flexible sealing window mechanism for aerospace optical imaging systems with a large diameter-to-thickness ratio according to claim 1, characterized in that, The light window pressure ring (4) is connected to the light window outer cylinder (6) by a threaded connection.

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